yum Error: Could not find the GPG Key necessary to validate pkg

yum 실행시 에러 발생 시 해결 방법 

Could not find the GPG Key necessary to validate pkg

On installing a package with yum on CentOS 3.8, i got error message

Downloading Packages
Getting perl-CGI-2.89-90.4.i386.rpm
perl-CGI-2.89-90.4.i386.r 100% |=========================| 188 kB 00:00
warning: rpmts_HdrFromFdno: V3 DSA signature: NOKEY, key ID 025e513b
Error: Could not find the GPG Key necessary to validate pkg /var/cache/yum/base/packages/perl-CGI-2.89-90.4.i386.rpm
Error: You may want to run yum clean or remove the file:
/var/cache/yum/base/packages/perl-CGI-2.89-90.4.i386.rpm
Error: You may also check that you have the correct GPG keys installed

The error is due to proper GPG keys is not installed on the server. You can get this from

http://mirror.centos.org/centos/

Since the server use CentOS 3.7, you need to download and install
 "RPM-GPG-KEY-CentOS-3"

You can install GPG keys with following command

# rpm --import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-3